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Packet vs message switching

Short answer

Message switching sends the entire message as a unit stored at each node, causing high delay. Packet switching divides the message into small packets, using pipelining to reduce delay. Packets share links fairly; only damaged packets are retransmitted. Packet switching suits real-time traffic better.

Write a short note on packet switching versus message switching.

Both use store-and-forward switching in which no dedicated path is reserved, but they differ in the unit that is sent.

  • Message switching: the entire message is sent as one unit from node to node. Each node receives the whole message, stores it (often on disk) and forwards it when the next link is free.
  • Packet switching: the message is divided into small packets of limited size which travel independently (or along a virtual circuit) and are reassembled at the destination.
PointMessage switchingPacket switching
Unit of transferWhole message (any size)Packets (fixed upper size)
Storage at nodesLarge, diskSmall, RAM buffer
DelayHigh, since entire message is received at each hopLower, pipelining of packets
Link occupancyLink blocked for long messagesShort, fair sharing of links
Error handlingWhole message is resentOnly damaged packet is resent
Suitable forTelegram, email, non-real-timeInternet, interactive and data traffic
ReorderingNot neededRequired at the destination
Header overheadOne headerHeader in every packet

For a message of M bits over k hops at rate R, message switching delay ≈ k·M/R, while packet switching with packet size p is about (M + (k−1)p)/R, which is much less.

✓ Answer checked by Claude Sonnet 5.5

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